The present invention relates to a tool and associated method for creating a perforation or cavity in a bone or bone structure in contact with a membrane, such as the sinus membrane. The perforation or cavity may be used to place an implant, particularly a dental implant.
Dental implants may be used to replace lost teeth. The body of dental implants is normally made of titanium. Dental implants are discussed in more detail in U.S. patent application Ser. No. 12/666,604 mentioned already above.
For the placement of an implant into the upper maxilla, the integrity of the sinus membrane (also known as the Schneider membrane) should be preserved while creating the perforation or cavity, and also afterwards. If, for the specific implant that is to be placed, the height of the alveolar crest is insufficient, the bone mass may be augmented by a sinus lift. The upper maxilla is then perforated, the sinus membrane is detached from the sinus floor and lifted, and bone grafting material is injected through the hole, so that this material is introduced in a pocket between the sinus floor and the raised sinus membrane. The injected bone grafting material is a structure capable of promoting the formation of bone around the implant. Finally, in the last phase, the implant is placed. During the complete process, perforating of the sinus membrane should be avoided.
A first known method to separate the sinus membrane from the sinus floor, and to lift the sinus membrane, uses a sinus lifting tool. Separation and lifting is then done mechanically.
Other known sinus lifting methods are those of Watzek and of Chen.
In Watzek's patent application WO 2009/062225, a surgical instrument is disclosed for introducing a flowable medium in the perforated upper maxilla for lifting the Schneider membrane from the sinus floor. First a set of special drills is used to perforate the upper maxilla; some drills have cutting and non-cutting portions in order to minimize the risk of perforating the Schneider membrane during drilling. Then, through the opening in the sinus floor, the flowable medium is introduced by the surgical instrument, to lift the Schneider membrane.
Watzek's patent application AT 504 780 discloses a drill having two portions: a peripheral, rotating portion that cuts, and a central portion. The central portion does not rotate and can move with respect to the peripheral portion in the axial direction of the drill. The central portion has at least one opening for a cooling fluid that cools the drill and the bone during the drilling operation. The cooling fluid also serves to remove the bone debris resulting from drilling. Near the end of the drilling phase, the central portion is moved forward in the axial direction, preferably by tapping, so that the small remaining portion of the sinus floor is broken off and is lifted by the central portion, together with the Schneider membrane.
Another technique is described in a publication by Pommer and Watzek, The International Journal of Oral & Maxillofacial Implants, p. 817-822, Vol. 24, Number 5, 2009. In this study, the sinus floor is punctured by a drill that has a rounded tip, in order to prevent perforating the sinus membrane, and a radiopaque gel is then injected through the puncture to separate and elevate the sinus membrane from the sinus floor.
Still another technique is disclosed in “An 8-Year Retrospective Study: 1,100 Patients Receiving 1,557 Implants Using the Minimally Invasive Hydraulic Sinus Condensing Technique”, L. Chen and J. Cha, Journal of Periodontology, March 2005, Vol. 76, Number 3, p. 482-491. A hole is drilled in the alveolar crest, and drilling ceases about 1 mm short of the sinus floor. The surgeon then downsizes to a 2 mm sinus bur for the purpose of forming a narrow conical shape at the end of the hole. While rotating, the 2 mm sinus bur is gently tapped through the cortical bone of the sinus floor just hard enough to form a pinhole. At this stage, hydraulic pressure from the handpiece of the drill is introduced to the surgical site, providing enough force to begin dissecting the membrane from the sinus floor. Once the membrane is loosened, hydraulic pressure is ceased. The membrane is then at rest but slightly detached.
Chen's patent application US 2009/0258328 discloses a dental implant method and apparatus, wherein a dental implant may be placed during one surgery by extracting a tooth from a socket, drilling a hole through crestal bone at the top of the socket, dissecting sinus membrane from the crestal bone by pulsing water through the hole and separating the sinus membrane from the crestal bone, then inserting bone mixture through the hole and between the sinus membrane and the crestal bone to increase the thickness of crestal bone. A hydraulic dental instrument is provided that pulses water through the drilled hole and separates the sinus membrane from the crestal bone.